1. Field of the Invention
This invention relates to a personal GPS navigation device. A personal GPS navigation device is any electronic device that can process GPS location data and display the location of the device on a map. The device may be a dedicated navigation device, or a general purpose electronic device, such as a personal digital assistant, smart phone, mobile telephone, laptop or palmtop computer. The device may be portable or fixed in a vehicle.
2. Description of the Prior Art
Personal navigation devices are becoming increasingly common. A particularly successful approach is to connect a PocketPC™ powered PDA (personal digital assistant) to a GPS receiver: the PDA, when running navigation software, becomes a GPS based personal navigation device. Another successful format is the dedicated GPS device, used by hikers, sailors etc. In some countries, mobile telephones will have to be equipped with a GPS receiver in order to be able to send the location of that telephone in the event of an emergency, greatly increasing the adopting of GPS technology as a mass market technology. Portable GPS receiver devices have also been used in personal safety devices as described in, for instance, U.S. Pat. No. 6,480,557 to Rog, et al. entitled “Portable GPS-receiver for a personal safety system”, the contents of which are hereby incorporated by reference.
GPS device have also been incorporated into road vehicles and integrated into road map data bases to provide navigation and vehicle tracking systems as described in, for instance, U.S. Pat. No. 4,837,700 to Ando, et al. entitied “Method and apparatus for processing data in a GPS receiving device in a road vehicle” and U.S. Pat. No. 5,225,842 to Brown, et al. entitled “Vehicle tracking system employing global positioning system (GPS) satellites”, the contents of both of which patents are hereby incorporated by reference.
One common feature of current personal GPS navigation devices is that they can display a GPS information screen, such as the screen shown in FIG. 1B. The GPS information screen shows: how many GPS satellite signals are being received and their individual strength at 3a; the location co-ordinates of the device at 3b; the speed of the device at 3c; the direction of movement of the device at 3d; the relative orientation of GPS satellites that a signal is being picked up from at 3e. The GPS information screen is useful when getting a first GPS fix. Once a fix has been established, most users then switch to the map mode, which causes a map to be displayed on the screen of the personal navigation device, indicating the location of the device with an arrow.